This invention relates to a method and apparatus for the attachment of a plastic container carrier sheet to the peripheral edges of a plurality of containers such as for soft drinks, which carrier sheet is adapted to have the plurality of containers bound into one set for convenience in carrying.
Among the carrier implements adapted to bind collectively the peripheral edges of a plurality of containers standing side by side on their flat ends for the purpose of ensuring convenience in carrying such containers, there is included a plastic container carrier sheet.
The sheet has a plurality of openings each surrounded by a circumferential portion. In the remaining intervening spaces of the sheet, there are provided a few (say, two) grip holes adapted for insertion of the fingers.
In an ordinary container such as a can for a soft drink, both or at least one of the opposite ends of the container has its end surface slightly bent inwardly except for the peripheral edge which circumferentially surrounds the end. The circumferential edge has a diameter slightly greater than the diameter of the main portion of the container which lies underneath. In most cases, these containers are made of aluminum.
The openings in the carrier sheet have a diameter smaller than the diameter of the main portion of the container. This sheet, therefore, is attached to the containers by forcibly expanding the circumferential portions of the openings to enlarge the openings and allow the peripheral edges to slide past the circumferential portions, then allowing the circumferential portions to resume their original shape thereby causing the inner surfaces of the circumferential portions to come into tight contact with the outer surfaces of the main portions of the containers. After the sheet has been attached as described above, the user has only to insert his thumb and index finger into the grip holes and get hold of the remaining portion of the sheet. In this manner, he can carry the containers conveniently without requiring a holder as would otherwise be required in carrying the plurality of containers.
As described above, the carrier sheet of such a construction proves to be highly useful. One problem which has been encountered by the conventional carrier sheet concerns the procedure involved when the openings are forcibly expanded out in effecting the attachment of the sheet to the containers. This forcible outward expansion of the openings, when made with the finger tips on all the containers, requires a considerable amount of force, though it is not impossible. From the standpoint of operational efficiency and in consideration of the large number of openings involved, such a manual procedure proves substantially impracticable.
To cope with the situation, therefore, there has been suggested a device capable of mechanically effecting this work (U.S. Pat. No. 3,628,305). This device is adapted so that two pins are inserted inside a pair of opposed openings and the pair of openings are expanded outwardly. This device, consequently, has the disadvantage that the circumferential portions tend to be torn, expanded unevenly, and brought into contact with the outer surfaces of the containers with insufficient tightness. Besides, this device entails a serious problem that when the pins are removed after the ends of the containers have been inserted into the expanded openings, the pins, which must be of gret rigidity, tend to scratch the containers, possibly to the extent of impairing their commercial value.
The object of the present invention is to provide a method and apparatus for easily and effectively attaching a carrier sheet to containers without entailing any damage to the carrier sheet or the containers.